This invention relates generally to power drive mechanisms for controlled and safe displacement of a folding wing section in an aircraft. More particularly, this invention relates to an improved wing fold actuator system designed for safe, fully reversible operation in response to alternative electrical or hydraulic power drive input. In addition, this invention relates to an improved latch pin unit for securely locking a folding wing section of an aircraft in a deployed position for normal flight operation.
Aircraft equipped with folding wing sections are generally known in the art, wherein an outboard wing section is hingedly connected to a fixed inboard wing section to permit pivoting movement between a generally horizontal deployed position for normal flight operations and a generally upright or vertical folded storage position. Such aircraft normally include a power driven actuator system for displacing the outboard wing section between the deployed and folded positions, in combination with one or more latch pins or similar lock devices for positively retaining the outboard wing section in the deployed condition during flight operations. In the past, the actuator mechanism has typically comprised an hydraulically powered mechanism designed for relatively rapid wing section displacement when the main hydraulic system of the aircraft is operational. However, hydraulic actuator systems have not provided satisfactory means for locking a folded or partially folded wing section in place in the event of hydraulic power interruption, such that the folded or partially folded wing section may fall uncontrollably to the deployed position thus creating a significant risk of injury to nearby personnel. Moreover, with hydraulically powered actuator systems, it has been necessary to provide an alternative hydraulic power source or other power drive apparatus to displace the folding wing section when the main hydraulic system of the aircraft is not operational.
Improved wing fold actuator systems have been proposed for displacing a folding wing section of an aircraft in response to alternative electrical or hydraulic power input. Such proposed systems have been intended primarily to facilitate wing section displacement in response to electrical power input when the main hydraulic system of the aircraft is nonoperational. Although electric drive actuator mechanisms generally displace the folding wing section at a relatively slow rate in comparison with an hydraulic drive mechanism, the capability for electric drive wing section displacement is highly beneficial when an hydraulic power source is inconvenient or unavailable. However, these dual drive actuator systems have tended to be relatively complex in terms of construction and operation, and further have not satisfactorily provided a simple and lightweight yet mechanically effective brake apparatus for locking the folding wing section in place in the event of power input interruption.
In addition, wing fold actuator systems in the prior art have frequently encountered unreliable operation of the latch pin or other lock device used to positively lock the folding wing section in the deployed position. That is, the latch pin or lock device has normally included an extensible latch component mounted on one of the adjacent inboard and outboard sections, and adapted to fit with relatively close tolerance through a lock port formed in a structural component on the other wing section. Secure engagement of the latch component within the lock port, with minimal freedom of movement, is essential for safe flight operations. Unfortunately, minor mechanical misalignment can result in incomplete engagement or nonengagement of the latch component such that proper wing section locking does not occur. Alternately, such mechanical misalignment can cause an engaged latch component to stick or bind in a locked position, thereby preventing wing section folding to the storage position.
The present invention overcomes the problems and disadvantages encountered in the prior art by providing an improved wing fold actuator system adapted for alternative electric or hydraulic power drive input, in combination with an improved brake unit for locking a folding wing section in place in the event of input power interruption. Moreover, the improved actuator system provides an improved latch pin unit having an extensible latch pin designed for reliable operation to lock and unlock the folding wing section.